Dynamic bandwidth management for load-based equipment in unlicensed spectrum

ABSTRACT

Systems and methods for dynamic bandwidth management for load-based equipment in unlicensed spectrum are disclosed. In an aspect, the disclosure provides a method for dynamic bandwidth management. The method includes obtaining training data by monitoring a plurality of channels in an unlicensed spectrum during a training period. The method further includes determining that at least a first channel of the plurality of channels is available for a transmission. The method also includes determining, based on the training data, whether to wait for an additional channel of the plurality of channels to become available for the transmission. Determining whether to wait may be based on either training data including probabilities that no additional channel is to become available within a transmission opportunity or a machine learning classification of a current state of the backoff counters based on training data including samples of previous states of backoff counters.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for patent claims priority to U.S. ProvisionalPatent Application No. 62/016,331, “Methods and Apparatus for DynamicBandwidth Management for Load-Based Equipment in Unlicensed Spectrum”filed Jun. 24, 2014, and assigned to the assignee hereof and herebyexpressly incorporated by reference herein in its entirety.

BACKGROUND

Aspects of this disclosure relate generally to telecommunications, andmore particularly to interference mitigation and the like.

A wireless communication network may be deployed to provide varioustypes of services (e.g., voice, data, multimedia services, etc.) tousers within a coverage area of the network. In some implementations,one or more access points (e.g., corresponding to different cells)provide wireless connectivity for access terminals (e.g., cell phones)that are operating within the coverage of the access point(s). In someimplementations, peer devices provide wireless connectively forcommunicating with one another.

Communication between devices in a wireless communication network may besubject to interference. For a communication from a first network deviceto a second network device, emissions of radio frequency (RF) energy bya nearby device may interfere with reception of signals at the secondnetwork device. For example, a Long Term Evolution (LTE) deviceoperating in an unlicensed RF band that is also being used by a Wi-Fidevice may experience significant interference from the Wi-Fi device,and/or can cause significant interference to the Wi-Fi device.

Over-the-air interference detection is employed in some wirelesscommunication networks in an attempt to mitigate such interference. Forexample, a device may periodically monitor (e.g., sniff) for energy inthe RF band used by the device. Upon detection of any kind of energy,the device may back-off the RF band for a period of time.

In practice, however, there may be problems with such a back-off or“listen-before-talk” (LBT) approach, at least in its conventionalimplementation. For example, for an LTE system operating in anunlicensed band with a Wi-Fi co-channel scenario where it is desired toavoid interference from Wi-Fi, the detected energy in the band might notbe from a Wi-Fi device, or might not be substantial. In addition, thedetected energy in the band may simply be adjacent channel leakage.Consequently, an LTE device may back off transmissions in the band evenwhen there is no Wi-Fi interference.

SUMMARY

Systems and methods for dynamic bandwidth management for load basedequipment operating in unlicensed spectrum are disclosed.

In an aspect, the disclosure provides a method for dynamic bandwidthmanagement. The method may include obtaining training data by monitoringa plurality of channels in an unlicensed spectrum during a trainingperiod. The method may further include determining that at least a firstchannel of the plurality of channels is available for a transmission.The method may also include determining, based on the training data,whether to wait for an additional channel of the plurality of channelsto become available for the transmission.

In an aspect, the disclosure provides an apparatus for dynamic bandwidthmanagement. The apparatus may include a channel assessing componentconfigured to obtain training data by monitoring a plurality of channelsin an unlicensed spectrum during a training period. The apparatus mayfurther include a training component configured to determine that atleast a first channel of the plurality of channels is available for atransmission. The apparatus may also include a channel selectingcomponent configured to determine, based on the training data, whetherto wait for an additional channel of the plurality of channels to becomeavailable for the transmission.

In another aspect, the disclosure provides an apparatus for dynamicbandwidth management. The apparatus may include means for obtainingtraining data by monitoring a plurality of channels in an unlicensedspectrum during a training period. The apparatus may further includemeans for determining that at least a first channel of the plurality ofchannels is available for a transmission. The apparatus may also includemeans for determining, based on the training data, whether to wait foran additional channel of the plurality of channels to become availablefor the transmission.

The disclosure provides, in an aspect, a computer readable mediumstoring computer executable code. The computer readable medium mayinclude code for obtaining training data by monitoring a plurality ofchannels in an unlicensed spectrum during a training period. Thecomputer readable medium may further include code for determining thatat least a first channel of the plurality of channels is available for atransmission. The computer readable medium may also include code fordetermining, based on the training data, whether to wait for anadditional channel of the plurality of channels to become available forthe transmission. The computer readable medium may be a non-transitorycomputer readable medium.

These and other aspects of the invention will become more fullyunderstood upon a review of the detailed description, which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofvarious aspects of the disclosure and are provided solely forillustration of the aspects and not limitation thereof.

FIG. 1 is a simplified block diagram of several sample aspects of acommunication system.

FIG. 2 is a flow diagram illustrating an example method of dynamicbandwidth management.

FIG. 3 illustrates an example of a scenario for dynamic bandwidthmanagement using multiple channels.

FIGS. 4 and 5 illustrate examples of data structures that may be usedfor storing a set of probabilities for a set of channel states.

FIG. 6 is a flow diagram illustrating an example method of dynamicbandwidth management using probabilistic channel access.

FIG. 7 illustrates an example of a scenario for dynamic bandwidthmanagement using machine learning classification.

FIG. 8 is a simplified block diagram of several sample aspects ofcomponents that may be employed in communication nodes.

FIG. 9 is a simplified diagram of a wireless communication system.

FIG. 10 is a simplified diagram of a wireless communication systemincluding small cells.

FIG. 11 is a simplified diagram illustrating coverage areas for wirelesscommunication.

FIG. 12 is a simplified block diagram of several sample aspects ofcommunication components.

FIG. 13 is a simplified block diagram of several sample aspects of anapparatus configured to support communication as taught herein.

DETAILED DESCRIPTION

The disclosure relates in some aspects to dynamic bandwidth managementfor determining whether to transmit in a “listen-before-talk” (LBT)scenario. A load-based equipment (LBE) may perform clear channelassessment (CCA) or enhanced clear channel assessment (eCCA) todetermine whether a particular channel is clear or available fortransmission. The LBE may also transmit using multiple channels if theyare clear or available for transmission. When the LBE determines that afirst channel is clear, the LBE may determine whether to transmit usingthe available channel(s) or to wait for additional channels to becomeavailable in order to increase the bandwidth of the transmission. If theLBE waits too long, however, total bandwidth may be reduced because ofunused transmission opportunities (e.g. the time spent waiting ratherthan transmitting) and lost transmission opportunities (e.g., previouslyclear channels are no longer available) while waiting for the additionalchannels to become available. By predicting the likelihood of anadditional channel becoming available, the LBE may increase availablebandwidth by waiting for additional channels when it is likely thatthose additional channels will become available.

The LBE may estimate the probability that an additional channel willbecome available based on historical trends in the radio environment.The LBE may monitor the availability of channels during a training phaseand use acquired information during a testing phase. In one aspect, theLBE may determine probabilities based on a number of available channelsor based on the combination of individual available channel(s). Inanother aspect, the LBE may classify a current transmission opportunitybased on the states of random backoff counters using a machine learningmodel.

Therefore, in aspects of the disclosure, methods and apparatus aredescribed in which training data may be obtained by monitoring multiplechannels in an unlicensed spectrum during a training period, determiningthat at least a first channel of the multiple channels is available fora transmission, and determining, based on the training data, whether towait for an additional channel of the multiple channels to becomeavailable for the transmission. In some instances, it may be beneficialto wait for the additional channel to become available and provideadditional bandwidth. In other instances, when the current availablechannels may not be clear for transmission for much longer, it may bebetter not to wait for the additional channel and transmit using thecurrently available bandwidth.

Aspects of the disclosure are provided in the following description andrelated drawings directed to specific disclosed aspects. Alternateaspects may be devised without departing from the scope of thedisclosure. Additionally, well-known aspects of the disclosure may notbe described in detail or may be omitted so as not to obscure morerelevant details. Further, many aspects are described in terms ofsequences of actions to be performed by, for example, elements of acomputing device. It will be recognized that various actions describedherein can be performed by specific circuits (e.g., application specificintegrated circuits (ASICs)), by program instructions being executed byone or more processors, or by a combination of both. Additionally, thesesequence of actions described herein can be considered to be embodiedentirely within any form of computer readable storage medium havingstored therein a corresponding set of computer instructions that uponexecution would cause an associated processor to perform thefunctionality described herein. Thus, the various aspects of thedisclosure may be embodied in a number of different forms, all of whichhave been contemplated to be within the scope of the claimed subjectmatter. In addition, for each of the aspects described herein, thecorresponding form of any such aspects may be described herein as, forexample, “logic configured to” perform the described action.

FIG. 1 illustrates several nodes of a sample communication system 100(e.g., a portion of a communication network). For illustration purposes,various aspects of the disclosure will be described in the context ofone or more access terminals, access points, and network entities thatcommunicate with one another. It should be appreciated, however, thatthe teachings herein may be applicable to other types of apparatuses orother similar apparatuses that are referenced using other terminology.For example, in various implementations access points may be referred toor implemented as base stations, NodeBs, eNodeBs, Home NodeBs, HomeeNodeBs, small cells, macro cells, femto cells, and so on, while accessterminals may be referred to or implemented as user equipment (UEs),mobile stations, and so on.

Access points in the system 100 provide access to one or more services(e.g., network connectivity) for one or more wireless terminals (e.g.,the access terminal 102 or the access terminal 104) that may beinstalled within or that may roam throughout a coverage area of thesystem 100. For example, at various points in time the access terminal102 may connect to the access point 106 or some other access point inthe system 100 (not shown). Similarly, the access terminal 104 mayconnect to the access point 108 or some other access point.

One or more of the access points may communicate with one or morenetwork entities (represented, for convenience, by the network entities110), including each other, to facilitate wide area networkconnectivity. Two or more of such network entities may be co-locatedand/or two or more of such network entities may be distributedthroughout a network.

A network entity may take various forms such as, for example, one ormore radio and/or core network entities. Thus, in variousimplementations the network entities 110 may represent functionalitysuch as at least one of: network management (e.g., via an operation,administration, management, and provisioning entity), call control,session management, mobility management, gateway functions, interworkingfunctions, or some other suitable network functionality. In someaspects, mobility management relates to: keeping track of the currentlocation of access terminals through the use of tracking areas, locationareas, routing areas, or some other suitable technique; controllingpaging for access terminals; and providing access control for accessterminals.

When the access point 106 (or any other devices in the system 100) usesa first RAT to communicate on a given resource, this communication maybe subjected to interference from nearby devices (e.g., the access point108 and/or the access terminal 104) that use a second RAT to communicateon that resource. For example, communication by the access point 106 viaLTE on a particular unlicensed RF band may be subject to interferencefrom Wi-Fi devices operating on that band. For convenience, LTE on anunlicensed RF band may be referred to herein as LTE/LTE Advanced inunlicensed spectrum, or simply LTE in the surrounding context.

In some systems, LTE in unlicensed spectrum may be employed in astandalone configuration, with all carriers operating exclusively in anunlicensed portion of the wireless spectrum (e.g., LTE Standalone). Inother systems, LTE in unlicensed spectrum may be employed in a mannerthat is supplemental to licensed band operation by providing one or moreunlicensed carriers operating in the unlicensed portion of the wirelessspectrum in conjunction with an anchor licensed carrier operating in thelicensed portion of the wireless spectrum (e.g., LTE SupplementalDownLink (SDL)). In either case, carrier aggregation may be employed tomanage the different component carriers, with one carrier serving as thePrimary Cell (PCell) for the corresponding user equipment (UE) (e.g., ananchor licensed carrier in LTE SDL or a designated one of the unlicensedcarriers in LTE Standalone) and the remaining carriers serving asrespective Secondary Cells (SCells). In this way, the PCell may providean FDD paired downlink and uplink (licensed or unlicensed), and eachSCell may provide additional downlink capacity as desired.

In an aspect of the present disclosure, a device operating in unlicensedspectrum may operate in a load-based system. In a load-based system,unlike a frame-based system, devices may not have set transmissiontimes. In a load-based system, an LBT procedure may be used to determinewhether one or more channels are available for transmission. Forexample, a device may perform CCA/eCCA to determine whether a channel isclear for transmission. When a channel is not clear, the device mayinitialize a random backoff counter for the channel. The random backoffcounter may countdown for each measured time slot where the channel isavailable. When the random backoff counter reaches 0, the device maytransmit for a limited transmission opportunity. The duration of thetransmission opportunity may be a multiple of the CCA time slotduration. During the transmission opportunity, other devices would beblocked by the transmission from also transmitting using the channel.Additionally, other channels on the same device, which are not beingused for a transmission, may also be blocked because of RF leakage.

Various standards may define the LBT procedures that must be used.Current standards, however, do not define procedures for a multi-channelscenario. Both LTE and Wi-Fi may use multiple channels. In Wi-Fi, thetransmission bandwidth can vary across 20, 40, 80, or even 160 MHz fromone packet to the next. This may be viewed as a transmission usingmultiple channels.

In general, LTE utilizes orthogonal frequency division multiplexing(OFDM) on the downlink and single-carrier frequency divisionmultiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition thesystem bandwidth into multiple (K) orthogonal subcarriers, which arealso commonly referred to as tones, bins, etc. Each subcarrier may bemodulated with data. In general, modulation symbols are sent in thefrequency domain with OFDM and in the time domain with SC-FDM. Thespacing between adjacent subcarriers may be fixed, and the total numberof subcarriers (K) may be dependent on the system bandwidth. Forexample, K may be equal to 128, 256, 512, 1024 or 2048 for systembandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz), respectively. Thesystem bandwidth may also be partitioned into subbands. For example, asubband may cover 1.08 MHz, and there may be 1, 2, 4, 8 or 16 subbandsfor system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

LTE may also use carrier aggregation. UEs (e.g., LTE-Advanced enabledUEs) may use spectrum of up to 20 MHz bandwidths allocated in a carrieraggregation of up to a total of 100 MHz (5 component carriers) used fortransmission and reception. For the LTE-Advanced enabled wirelesscommunication systems, two types of carrier aggregation (CA) methodshave been proposed, continuous CA and non-continuous CA. Continuous CAoccurs when multiple available component carriers are adjacent to eachother. On the other hand, non-continuous CA occurs when multiplenon-adjacent available component carriers are separated along thefrequency band. Both non-continuous and continuous CA may aggregatemultiple component carriers to serve a single unit of LTE-Advanced UEs.

In a blended radio environment such as system 100, different RATs maymake use of different channels at different times. Because differentRATs are sharing the spectrum and operating partly independently ofothers, access to one channel may not imply access to another channel.Accordingly, a device capable of transmitting using multiple channelsmay need to determine whether each channel is available beforetransmitting. In order to increase bandwidth and throughput, it may bebeneficial in some situations to wait for an additional channel tobecome available rather than transmitting using currently availablechannel(s).

In an aspect, an LBE such as access terminal 102 or access point 106 mayinclude a bandwidth manager 120 for determining which channels to usefor a transmission. It should be appreciated that any wireless deviceacting as an LBE may include a bandwidth manager 120. In an aspect, adevice may act as a LBE part of the time, or while operating inparticular modes. For example, access point 106 may act as a LBE whenoperating using a first RAT, but may operate in a frame based mannerwhen operating using a second RAT.

Bandwidth manager 120 may include hardware or means for determining thechannels or bandwidth to use for transmissions. In particular, bandwidthmanager 120 may determine whether to transmit using currently availablechannels, or to wait for additional channels to become available.Bandwidth manager 120 may include a channel assessing component 122, atraining component 126, and a channel selecting component 132. In anaspect, the term “component” as used herein may be one of the parts thatmake up a system, may be hardware or software, and may be divided intoother components.

The channel assessing component 122 may include hardware configured todetermine whether a channel is available for a transmission. Forexample, channel assessing component 122 may include a receiver (notshown) configured to measure received signal energy in a channel.Channel assessing component 122 may determine that a channel is clearwhen the signal energy falls below a threshold value. In an aspect,channel assessing component 122 may determine whether a channel isavailable according to regulations or a standard. For example, EN301.893 may define LBT procedures. IEEE 802.11 and 802.15 standards maydefine clear channel assessment (CCA) procedures. Generally, the CCAprocedures may involve monitoring a channel for a CCA duration or timeslot, for example 20 microsecond (μs). If the time slot is clear (e.g.,the communications medium is available or accessible), the device maybegin using the channel. If the channel is not clear, the device maydetermine a random backoff counter for the channel. Each time the devicedetects a clear time slot, the random backoff counter is decremented.

Channel assessing component 122 may maintain backoff counters 124, whereeach of the backoff counters 124 corresponds to a different channel. Forexample, the backoff counters 124 may be a memory configured to storevalues for each channel. The channel assessing component 122 my assign arandom value to a backoff counter 124 whenever there is data totransmit, but the channel is busy. The channel assessing component 122may decrement each backoff counter 124 when the corresponding channel isclear for a time slot. The corresponding channel may be consideredavailable when the backoff counter reaches 0. Accordingly, when an LBEwould like to use multiple channels for a transmission, the channels maybecome available at different times. In an aspect, the backoff counters124 may also be used to measure how long a channel has been available.For example, the channel assessing component 122 may continue todecrement the backoff counters 124 into negative numbers, where anegative number indicates how long the corresponding channel has beenavailable. In another aspect, the channel assessing component 122 mayinclude a flag or similar functionality to indicate whether the channelis available and to increment the backoff counters 124 to indicate howlong the corresponding channel has been available.

Training component 126 may include hardware configured to monitor aplurality of channels during a training period. For example, trainingcomponent 126 may include a processor (not shown) configured to processinformation obtained by channel assessing component 122. The trainingperiod may be a time period prior to a transmission. The training periodmay include times when the LBE is idle. The training period may alsoinclude times when the LBE is actively transmitting. In an aspect, thetraining period may be a sliding window preceding a transmission. Thetraining component 126 may capture information regarding the status ofthe channels during the training period that may be used to predictwhether the LBE will be able to increase bandwidth or throughput bywaiting for an additional channel to become available before the end ofa transmission opportunity when a subset of channels are alreadyavailable for transmission.

In an aspect, the training component 126 may include probabilities 128.The probabilities 128 may be stored in a memory accessible to othercomponents of the bandwidth manager 120. The probabilities 128 mayindicate a probability of an additional channel becoming availableduring a transmission opportunity and/or the probability of noadditional channels becoming available during a transmissionopportunity. In other words, the probabilities 128 may indicate theprobability that acquiring the available channels at the current timeslot would be a good transmission opportunity. In an aspect, a goodtransmission opportunity may be defined as a transmission opportunitystarting at a time slot where the total number of available channelsdoes not increase during the transmission opportunity. The probabilities128 may be determined by training component 126 based on real and/orhypothetical transmission opportunities during the training period. Forexample, the training component 126 may evaluate a real transmission todetermine whether an additional channel became available during thetransmission opportunity. The training component 126 may likewiseevaluate periodic hypothetical transmission opportunities during thetraining period. The probabilities 128 may be based on the percentage oftransmissions where additional channels did and did not become availableduring the transmission opportunity.

In another aspect, the training component 126 may include samples 130.The samples 130 may record the state of the backoff counters 124 duringthe training period. The samples 130 may be stored in a memory. Thetraining component 126 may store the value of each backoff counter 124during a time slot along with an evaluation of whether starting atransmission at the time slot would have been good. In other words, thetraining component 126 may determine whether the transmission time ofthe sample was a good transmission time. The training component 126 mayretroactively evaluate the samples 130 after the transmissionopportunity following the time slot to determine whether starting atransmission at the time slot of the sample was a good time to start atransmission. A determination that starting a transmission at a timeslot would have been good may indicate that no additional channelsbecame available during the transmission opportunity following the timeslot. In another aspect, determining that a time slot is good mayinclude determining that the number of available channels was notgreater at any time slot during the transmission opportunity followingthe time slot. In another aspect, determining that a time slot is goodmay include determining that a bandwidth of the available channels wasnot greater at any time slot during the transmission opportunityfollowing the time slot.

Channel selecting component 132 may include hardware configured todetermine whether to transmit using currently available channels. Forexample, channel selecting component 132 may include a processor (notshown) configured to perform the various functions of the channelselecting component 132. In an aspect, channel selecting component 132may use information determined by channel assessing component 122 for acurrent time slot and information from training component 126 todetermine whether to transmit using the currently available channels.

In an aspect, channel selecting component 132 may determine whether totransmit based on the probabilities 128. The channel selecting component132 may obtain a probability 128 corresponding to the current channelconditions and determine whether to transmit based on the probability.For example, the channel selecting component 132 may compare theprobability to a threshold value to determine whether to transmit. In anaspect, the channel selecting component 132 may include a random numbergenerator (RNG) 134 configured to randomly or pseudo-randomly generate anumber. The channel selecting component 132 may compare the random orpseudo-random number to the probability. For example, if the number isless than a probability that no additional channels will becomeavailable, then the channel selecting component 132 may determine totransmit with the currently available channels.

In an aspect, channel selecting component 132 may determine whether totransmit with a currently available channel(s) based on the samples 130.The channel selecting component 132 may include a machine learningclassifier 136 to determine whether starting a transmission with thecurrent state of the backoff counters 124 is likely to be good. Thedefinition of a good state of the backoff counters 124 may be the sameas the definition used to evaluate the samples 130; however, because theevaluation of the time slot may not be known for certain until after thetransmission opportunity, the classifier 136 may be used to predict theevaluation. Generally, the classifier 136 may compare the currentcounter state vector with the history of training samples 130. Theclassifier 136 may determine a class boundary based on the samples 130and determine how to classify the current state vector based on theclass boundary. Various machine learning classifiers or models known inthe art may be used. Example classifiers include logistic regression,support vector machine (SVM), Kernel-SVM, Linear Discriminant Analysis,Naïve Bayes classifier, neural networks, k-nearest neighbor, Gaussianmixture models, and Radial basis function classifier.

FIG. 2 is a flow diagram illustrating an example method 200 of dynamicbandwidth management. The method may be performed by an LBE (e.g., theaccess terminal 102 or the small cell access point 106 illustrated inFIG. 1).

At block 210, the method 200 may include obtaining training data bymonitoring a plurality of channels in an unlicensed spectrum during atraining period. The training component 126 may obtain training data bymonitoring the plurality of channels during the training period. Thetraining component 126 may use information determined by the channelassessing component 122 to monitor the plurality of channels. In anaspect, obtaining the training data may include estimating for a set ofchannels states, a corresponding set of probabilities indicatinglikelihoods that an additional channel will become available within atransmission opportunity. In another aspect, obtaining the training datamay include collecting samples for potential transmission times havingat least one available channel. The samples may include states of aplurality of backoff counters 124 corresponding to the plurality ofchannels.

At block 220, the method 200 may include determining that at least afirst channel of the plurality of channels is available for atransmission. The channel assessing component 122 may determine that afirst channel of the plurality of channels is available for thetransmission. The channel assessing component 122 may assess the channelbased on presence of data for the transmission. The determination thatthe channel is available may include determining that a backoff counter124 has reached 0.

At block 230, the method 200 may include determining, based on thetraining data, whether to wait for an additional channel of theplurality of channels to become available. The channel selectingcomponent 132 may determine whether to wait for an additional channel ofthe plurality of channels to become available. In an aspect, the channelselecting component 132 may use the probabilities 128 to estimate aprobability that an additional channel will become available during atransmission opportunity. The channel selecting component 132 may thendetermine whether to transmit during the transmission opportunity basedon the probability of an additional channel becoming available. Inanother aspect, the channel selecting component 132 may use theclassifier 136 to determine whether to transmit based on the samples130. The classifier 136 may classify a current state of the backoffcounters 124 as either a good transmission opportunity or a badtransmission opportunity based on the samples 130. As discussed above,the classification of a transmission opportunity as “good” may indicatethat the classifier 136 predicts that the number of channels or thebandwidth of the channels will not increase during a transmissionopportunity. Conversely, a classification of a transmission opportunityas “bad” may indicate that the classifier 136 predicts that anadditional channel will become available during the transmissionopportunity.

At block 240, the method 200 may optionally include transmitting usingat least the first channel. A transmitter in an LBE (e.g., accessterminal 102) may transmit using at least the first channel. Thetransmitter may also transmit using any additional channels selected bythe channel selecting component 132. The transmitter may begin thetransmission immediately after determining not to wait. If the channelselecting component 132 determines to wait, the transmission may takeplace after another channel becomes available, or after waiting for theduration of a transmission opportunity.

FIG. 3 illustrates an example of a scenario 300 for dynamic bandwidthmanagement using multiple channels as described with respect to FIGS. 1and 2. Three channels are illustrated in FIG. 3 with respective counters310, but it should be apparent that a system may use additionalchannels. When a channel is busy and an LBE has data to transmit, thebackoff counter 124 corresponding to the channel may be assigned arandom value. For example, at time 0, channel 1 (CH1) may have a countervalue of 3, channel 2 (CH2) may have a counter value of 5, and channel 3(CH3) may have a counter value of 7. The channel may be checked forusage every CCA time slot. The counters 310 are illustrated for eachtime slot when the channel is not available. When no usage of a channelis detected, the counters may be decremented. It should be noted that achannel may not be used, but may not be available because the associatedcounter 310 has not reached 0.

At time T1, channel 1 may become available. The dynamic bandwidthmanager 120 may determine whether to transmit during the transmissionopportunity 320 starting at T1 using the available channel 1, or to waitfor an additional channel (e.g., channel 2 or channel 3) to becomeavailable. A transmission opportunity may be a maximum amount of time anLBE may use a channel for transmission before it must perform a CCA orallow another device to use the channel. Waiting for an additionalchannel to become available may increase available bandwidth for thetransmission during a transmission opportunity, and therefore increasethroughput. For example, at time T2, channel 2 may become available.Assuming channel 1 and channel 2 have the same bandwidth, the additionalchannel may double the available bandwidth. Accordingly, the LBE mayincrease throughput by waiting for the transmission opportunity 330beginning at time T2.

At time T2, the dynamic bandwidth manager 120 may also determine whetherto wait for channel 3 to also become available. If channel 3 becomesavailable at time T3, the dynamic bandwidth manager 120 may furtherincrease the bandwidth by using three channels during transmissionopportunity 340. If, however, channel 3 did not become available untiltime T4, the bandwidth manager component 120 may maximize throughput bystarting a first transmission at T2, and a second transmission at T4.

FIG. 4 illustrates an example of a data structure 400 that may be usedfor storing a set of probabilities for a set of channel states inaccordance with the dynamic bandwidth management using multiple channelsas described with respect to FIGS. 1 and 2. As illustrated in FIG. 4,the set of channel states 410 may be the number of available channels ina system (e.g., system 100) having a maximum of N channels. Theprobability 420 may indicate a probability that no additional channelswill become available during a transmission opportunity when the channelstate 410 is the current channel state. In other words, the probability420 indicates the probability that starting a transmission in thechannel state 410 is a good choice. The probability 420 for N channelsmay be 1 because no additional channels can become available. The othervalues for probability 420 may be based on observations during thetraining period. Generally, it is expected that the fewer channels thatare currently available, the less likely starting a transmission is agood choice.

FIG. 5 illustrates another example of a data structure 500 that may beused for storing a set of probabilities for a set of channel states inaccordance with the dynamic bandwidth management using multiple channelsas described with respect to FIGS. 1 and 2. As illustrated in FIG. 5,the set of channel states 510 may be based on the number of availablechannels and combinations of available channels. FIG. 5 illustratescombinations for 4 possible channels; however, the data structure 500may be expanded for N channels to include 2^(N)−1 entries. Datastructure 500 may provide a probability 520 for each combination ofavailable channels. Data structure 500 may provide greater precisionthan data structure 400 in estimating the probability that an additionalchannel will become available. For example, when one channel is usedonly infrequently, the probability that the channel will becomeavailable may be greater. For example, in FIG. 5, channel 4 may be usedinfrequently and be generally associated with higher probabilities. Thedata structure 500 may require additional samples or a longer trainingperiod to become reliable. In an aspect, the data structure 400 may beused until sufficient training data is available.

FIG. 6 is a flow diagram illustrating an example method 600 of dynamicbandwidth management. The method 600 may be performed by the dynamicbandwidth manager 120 of an LBE.

In block 605, the method 600 may include testing a potentialtransmission time during a training period. The potential transmissiontime may be a hypothetical transmission time or the transmission time ofan actual transmission. The training component 126 may determine, foreach potential transmission time, whether an additional channel becameavailable during a transmission opportunity following the transmissiontime. Block 605 may be performed for a plurality of transmission times.The training component 126 may evaluate each transmission time as eithergood or bad, based on whether an additional channel became availableduring the transmission opportunity.

In block 610, the method 600 may include determining a probability foreach channel state. The training component 126 may associate eachtransmission time tested in block 605 with a channel state 410 or 510based on the available channels at the transmission time. The trainingcomponent 126 may then determine a portion of the plurality oftransmission times when an additional channel became available duringthe transmission opportunity. For example, the training component 126may determine a probability 420 or 520 by dividing the number oftransmission times when no additional channels became available by thetotal number of transmission times matching the channel state.

In block 615, the method 600 may include selecting a probability 420 or520 for a current transmission based on the channel state 410 or 510.For example, the channel selecting component 128 may obtain theprobability from data structure 400 or 500 corresponding to the currentchannel state.

In block 620, the method 600 may include determining whether a randomnumber is less than a probability threshold. For example, the RNG 134may generate a random or pseudo-random number between 0 and 1. Therandom or pseudo-random number may then be compared to a probabilitythreshold value. In an aspect, the probability threshold value may bethe probability. The probability threshold value, however, may also beweighted by other factors affecting throughput such as the relativebandwidth of the channels, length of a transmission opportunity, andamount of data to transmit. If the random or pseudo-random number isless than the probability threshold value, the method 600 may proceed toblock 625 using the available channels as the selected channels. If therandom or pseudo-random number is greater than the probability thresholdvalue, the method 600 may wait for an additional channel to becomeavailable and proceed to block 630. It should be apparent that inverseprobabilities and inequalities, other channel states, and/or otherrepresentations of probabilities may be used.

In block 630, the method 600 may include determining whether anavailable channel has become busy. For example, another device may begina transmission and an available channel may no longer be available. Thechannel assessing component 122 may determine that a channel has becomebusy based on signal energy received on the channel. If a channel hasbecome busy, the number of available channels and the probability thatan additional channel will become available may change. Accordingly, themethod 600 may proceed to block 640 when an available channel has becomebusy. The method 600 may proceed to block 635 when no available channelhas become busy.

In block 635, the method 600 may include determining whether a busychannel has become available. The channel assessing component 122 maydetermine whether a busy channel has become available. As discussedabove, the channel assessing component 122 may determine that a channelhas become available when a backoff counter for the channel has reached0. When a busy channel becomes available, the probability that anadditional channel will also become available may change. Also, theadditional available channel may present a good opportunity to transmit.If a busy channel has become available, the method 600 may proceed toblock 640 then through blocks 615 and 620 to determine whether totransmit. If no busy channel has become available, the method 600 mayproceed to block 645.

In block 640, the method 600 may include updating the probabilitiesbased on changed channel conditions. The probabilities may be updatedduring the action phase in order to keep the probabilities 128 accuratefor a changing radio environment. If an initially available channelbecame busy and remained busy during the transmission opportunity and noadditional channel became available, the initial channel state may beassociated with a good opportunity to transmit. If an initiallyavailable channel became busy and remained busy during the transmissionopportunity, but a new channel also became available, the initialchannel state may also be associated with a good opportunity totransmit. If an initially available channel became temporarily busy, butbecame available again before the end of the transmission opportunity,and another channel also became available, the initial channel state maybe associated with a bad opportunity to transmit. The probability 128corresponding to the initial channel state may be updated. The method600 may return to block 615 and select a new probability 420 or 520based on an updated channel state. The method 600 may then proceed tostep 620 to determine whether to transmit using the currently availablechannels based on the probability.

At block 645, the method 600 may include determining that a transmissionopportunity has ended. The channel selecting component 132 may determinethat a transmission opportunity has ended. The transmission opportunitymay be measured from the time when the first channel became available.The channel selecting component 132 may determine to stop waiting foradditional channels to become available. The channel selecting component132 may select the available channels for the transmission. The methodmay then proceed to block 650.

In block 650, the method 600 may include transmitting using selectedchannels. The transmission may use the selected channels for theduration of a transmission opportunity. By transmitting using theselected channels, an LBE may effectively prevent other devices fromusing the selected channels. The transmission may also prevent the LBEfrom transmitting using additional channels, that is, the LBE may beself-blocked on any channel that becomes available after the LBE startstransmitting. The method 600 may end after the transmission.Alternatively, the method 600 may return to block 640 to update theprobabilities 128.

FIG. 7 illustrates an example of a scenario for dynamic bandwidthmanagement using a machine learning classifier. Similarly to FIG. 3,discussed above, FIG. 7 illustrates three channels (CH1, CH2, and CH3);however, it should be appreciated that other numbers of channels may beused. FIG. 7 illustrates the state of the backoff counters 124 for eachCCA time slot. In an illustrated aspect, an available channel may berepresented by a number less than or equal to zero. Negative numbers mayrepresent an amount of time (e.g. a number of CCA periods) that thechannel has been available. If a previously available channel becomesbusy, the negative number for that channel may freeze at the currentvalue and not further decrement until the channel is available again. Inanother aspect, if a previously available channel becomes busy, thecounter may be reset to 1 to indicate that the channel may be used assoon as it is detected as available. The counter may not reset to a newrandom positive number because the LBE is not required to wait when thechannel becomes available. It should be apparent that the amount of timethat a channel has been available may be represented in alternativemanners. For example, the amount of time that a channel has beenavailable may be represented by a flag associated with a positivecounter or by a separate counter.

During a training period, the training component 126 (FIG. 1) maycollect samples 130 of the states of the counters 124. A sample 130 maybe illustrated in FIG. 7 by a vertical row of time slots. A sample 130may also include an evaluation associated with the states of the backoffcounters 124 (FIG. 1). The evaluation may be determined retroactively,after a transmission opportunity 720 following a time slot. The trainingcomponent 126 may not collect samples when no channel is available. Forexample, the training component 126 may not collect any samples betweentime T0 and time T1 because all of the channels are busy. At time T1,channel 1 may become available and training component 126 may collect asample. The sample may include a vector indicating the states of thebackoff counters. For example, a sample 130 a at time T1 may indicate(0, 2, 4, Bad). In an aspect, the vector may be ordered based on thebackoff counters rather than the channels. For example, the states ofthe backoff counters may be placed in ascending order. The sample 130 aat T1 may be labeled “bad” because an additional channel, channel 2,becomes available at time T2, which is within a transmission opportunity720 following T1. As illustrated in FIG. 7, the samples between T1 andT2 may also be labeled “bad”. At time T2, the sample 130 b may indicate(−5, 0, 2, Good) because the number of available channels remains at 2,for the remainder of the transmission opportunity 720. If the status ofchannels 1 and 3 do not change after T2, the samples following T2 duringthe transmission opportunity 720 may also be labeled “good.” In anaspect, the training component 126 may only collect samples during afirst transmission opportunity of a first channel to become available.For example, the training component 126 may collect samples only duringtransmission opportunity 720. The channel selecting component 132 maydetermine to transmit using available channels at the end of thetransmission opportunity 720 regardless of whether an additional channelmay become available.

In another aspect, the training component 126 may collect samples aftera first transmission opportunity has expired or the transmissionopportunity 720 may be longer. Additional examples of possibleclassifications of samples are provided. As an example, at a time T3,channel 1 may become busy leaving only channel 2 available. The sample130 c at time T3 may indicate (1, −5, 1, Bad) or (−5, 1, 1, Bad) becauseeither channel 1 or channel 3 may become available within thetransmission opportunity 730 beginning at time T2. For example, at atime T4 channel 3 may become available, resulting in 2 availablechannels again. Accordingly, at time T3, when only one channel isavailable, the channel selecting component 132 is better waiting for anadditional channel. Moreover, at time T4, the sample 130 d may indicate(1, −6, 0, Good) or (−6, −0, 1, Good) because 2 channels is the maximumnumber of channels available in the transmission opportunity 740. Forexample at a time T5, another device may begin transmitting usingchannels 2 and 3, resulting in no available channels. Times T3, T4, andT5 may all occur within the transmission opportunity 720, or a newtransmission opportunity may be measured whenever a channel becomesavailable. For example, a transmission opportunity 730 may be measuredfrom time T2 when channel 2 becomes available and transmissionopportunity 740 may be measured from time T4 when channel 3 becomesavailable.

In an aspect, the collected samples may be further sorted and/orprocessed. For example, the samples may be sorted into sets based on thenumber of available channels. A machine learning classifier may beapplied to only a set of the samples to reduce the complexity of theclassification model. As another example, the values of the counters maybe reordered within a sample such that the counters for the availablechannels are listed first and the unavailable channels listedafterwards. The counters may be ordered in ascending order. Reorderingthe counters may reduce complexity of the classification model.

FIG. 8 illustrates several sample components (represented bycorresponding blocks) that may be incorporated into an apparatus 802, anapparatus 804, and an apparatus 806 (e.g., corresponding to an accessterminal, an access point, and a network entity, respectively) tosupport dynamic bandwidth adaptation operations as taught herein. Theapparatus 802 and the apparatus 804, for example, may include abandwidth manager 120 for determining which channels to use for atransmission. It should be appreciated that these components may beimplemented in different types of apparatuses in differentimplementations (e.g., in an ASIC, in an SoC, etc.). The describedcomponents also may be incorporated into other apparatuses in acommunication system. For example, other apparatuses in a system mayinclude components similar to those described to provide similarfunctionality. Also, a given apparatus may contain one or more of thedescribed components. For example, an apparatus may include multipletransceiver components that enable the apparatus to operate on multiplecarriers and/or communicate via different technologies.

The apparatus 802 and the apparatus 804 each include at least onewireless communication device (represented by the communication devices808 and 814 (and the communication device 820 if the apparatus 804 is arelay)) for communicating with other nodes via at least one designatedradio access technology. Each communication device 808 includes at leastone transmitter (represented by the transmitter 810) for transmittingand encoding signals (e.g., messages, indications, information, and soon) and at least one receiver (represented by the receiver 812) forreceiving and decoding signals (e.g., messages, indications,information, pilots, and so on). Similarly, each communication device814 includes at least one transmitter (represented by the transmitter816) for transmitting signals (e.g., messages, indications, information,pilots, and so on) and at least one receiver (represented by thereceiver 818) for receiving signals (e.g., messages, indications,information, and so on). Additionally, each of the communication devices808 and 814 may include a bandwidth manger 120 for determining whetherto wait for additional channel(s) to become available for atransmission. If the apparatus 804 is a relay access point, eachcommunication device 820 may include at least one transmitter(represented by the transmitter 822) for transmitting signals (e.g.,messages, indications, information, pilots, and so on) and at least onereceiver (represented by the receiver 824) for receiving signals (e.g.,messages, indications, information, and so on).

A transmitter and a receiver may comprise an integrated device (e.g.,embodied as a transmitter circuit and a receiver circuit of a singlecommunication device) in some implementations, may comprise a separatetransmitter device and a separate receiver device in someimplementations, or may be embodied in other ways in otherimplementations. In some aspects, a wireless communication device (e.g.,one of multiple wireless communication devices) of the apparatus 804comprises a network listen module.

The apparatus 806 (and the apparatus 804 if it is not a relay accesspoint) includes at least one communication device (represented by thecommunication device 826 and, optionally, 820) for communicating withother nodes. For example, the communication device 826 may comprise anetwork interface that is configured to communicate with one or morenetwork entities via a wire-based or wireless backhaul. In some aspects,the communication device 826 may be implemented as a transceiverconfigured to support wire-based or wireless signal communication. Thiscommunication may involve, for example, sending and receiving: messages,parameters, or other types of information. Accordingly, in the exampleof FIG. 8, the communication device 826 is shown as comprising atransmitter 828 and a receiver 830. Similarly, if the apparatus 804 isnot a relay access point, the communication device 820 may comprise anetwork interface that is configured to communicate with one or morenetwork entities via a wire-based or wireless backhaul. As with thecommunication device 826, the communication device 820 is shown ascomprising a transmitter 822 and a receiver 824.

The apparatuses 802, 804, and 806 also include other components that maybe used in conjunction with dynamic bandwidth adaptation operations astaught herein. The apparatus 802 includes a processing system 832 forproviding functionality relating to, for example, communicating with anaccess point to support dynamic bandwidth management as taught hereinand for providing other processing functionality. The apparatus 804includes a processing system 834 for providing functionality relatingto, for example, dynamic bandwidth management as taught herein and forproviding other processing functionality. The apparatus 806 includes aprocessing system 836 for providing functionality relating to, forexample, dynamic bandwidth management as taught herein and for providingother processing functionality. The apparatuses 802, 804, and 806include memory devices 838, 840, and 842 (e.g., each including a memorydevice), respectively, for maintaining information (e.g., informationindicative of reserved resources, thresholds, parameters, and so on). Inaddition, the apparatuses 802, 804, and 806 include user interfacedevices 844, 846, and 848, respectively, for providing indications(e.g., audible and/or visual indications) to a user and/or for receivinguser input (e.g., upon user actuation of a sensing device such a keypad,a touch screen, a microphone, and so on).

For convenience, the apparatus 802 is shown in FIG. 8 as includingcomponents that may be used in the various examples described herein. Inpractice, the illustrated blocks may have different functionality indifferent aspects.

The components of FIG. 8 may be implemented in various ways. In someimplementations, the components of FIG. 8 may be implemented in one ormore circuits such as, for example, one or more processors and/or one ormore ASICs (which may include one or more processors). Here, eachcircuit may use and/or incorporate at least one memory component forstoring information or executable code used by the circuit to providethis functionality. For example, some or all of the functionalityrepresented by blocks 808, 832, 838, and 844 may be implemented byprocessor and memory component(s) of the apparatus 802 (e.g., byexecution of appropriate code and/or by appropriate configuration ofprocessor components). Similarly, some or all of the functionalityrepresented by blocks 814, 820, 834, 840, and 846 may be implemented byprocessor and memory component(s) of the apparatus 804 (e.g., byexecution of appropriate code and/or by appropriate configuration ofprocessor components). Also, some or all of the functionalityrepresented by blocks 826, 836, 842, and 848 may be implemented byprocessor and memory component(s) of the apparatus 806 (e.g., byexecution of appropriate code and/or by appropriate configuration ofprocessor components).

Some of the access points referred to herein may comprise low-poweraccess points. In a typical network, low-power access points (e.g.,femto cells) are deployed to supplement conventional network accesspoints (e.g., macro access points). For example, a low-power accesspoint installed in a user's home or in an enterprise environment (e.g.,commercial buildings) may provide voice and high speed data service foraccess terminals supporting cellular radio communication (e.g., CDMA,WCDMA, UMTS, LTE, etc.). In general, these low-power access pointsprovide more robust coverage and higher throughput for access terminalsin the vicinity of the low-power access points.

As used herein, the term low-power access point refers to an accesspoint having a transmit power (e.g., one or more of: maximum transmitpower, instantaneous transmit power, nominal transmit power, averagetransmit power, or some other form of transmit power) that is less thana transmit power (e.g., as defined above) of any macro access point inthe coverage area. In some implementations, each low-power access pointhas a transmit power (e.g., as defined above) that is less than atransmit power (e.g., as defined above) of the macro access point by arelative margin (e.g., 10 dBm or more). In some implementations,low-power access points such as femto cells may have a maximum transmitpower of 20 dBm or less. In some implementations, low-power accesspoints such as pico cells may have a maximum transmit power of 24 dBm orless. It should be appreciated, however, that these or other types oflow-power access points may have a higher or lower maximum transmitpower in other implementations (e.g., up to 1 Watt in some cases, up to10 Watts in some cases, and so on).

Typically, low-power access points connect to the Internet via abroadband connection (e.g., a digital subscriber line (DSL) router, acable modem, or some other type of modem) that provides a backhaul linkto a mobile operator's network. Thus, a low-power access point deployedin a user's home or business provides mobile network access to one ormore devices via the broadband connection.

Various types of low-power access points may be employed in a givensystem. For example, low-power access points may be implemented as orreferred to as femto cells, femto access points, small cells, femtonodes, home NodeBs (HNBs), home eNodeBs (HeNBs), access point basestations, pico cells, pico nodes, or micro cells.

For convenience, low-power access points may be referred to simply assmall cells in the discussion that follows. Thus, it should beappreciated that any discussion related to small cells herein may beequally applicable to low-power access points in general (e.g., to femtocells, to micro cells, to pico cells, etc.).

Small cells may be configured to support different types of accessmodes. For example, in an open access mode, a small cell may allow anyaccess terminal to obtain any type of service via the small cell. In arestricted (or closed) access mode, a small cell may only allowauthorized access terminals to obtain service via the small cell. Forexample, a small cell may only allow access terminals (e.g., so calledhome access terminals) belonging to a certain subscriber group (e.g., aclosed subscriber group (CSG)) to obtain service via the small cell. Ina hybrid access mode, alien access terminals (e.g., non-home accessterminals, non-CSG access terminals) may be given limited access to thesmall cell. For example, a macro access terminal that does not belong toa small cell's CSG may be allowed to access the small cell only ifsufficient resources are available for all home access terminalscurrently being served by the small cell.

Thus, small cells operating in one or more of these access modes may beused to provide indoor coverage and/or extended outdoor coverage. Byallowing access to users through adoption of a desired access mode ofoperation, small cells may provide improved service within the coveragearea and potentially extend the service coverage area for users of amacro network.

Thus, in some aspects the teachings herein may be employed in a networkthat includes macro scale coverage (e.g., a large area cellular networksuch as a third generation (3G) network, typically referred to as amacro cell network or a WAN) and smaller scale coverage (e.g., aresidence-based or building-based network environment, typicallyreferred to as a LAN). As an access terminal (AT) moves through such anetwork, the access terminal may be served in certain locations byaccess points that provide macro coverage while the access terminal maybe served at other locations by access points that provide smaller scalecoverage. In some aspects, the smaller coverage nodes may be used toprovide incremental capacity growth, in-building coverage, and differentservices (e.g., for a more robust user experience).

In the description herein, a node (e.g., an access point) that providescoverage over a relatively large area may be referred to as a macroaccess point while a node that provides coverage over a relatively smallarea (e.g., a residence) may be referred to as a small cell. It shouldbe appreciated that the teachings herein may be applicable to nodesassociated with other types of coverage areas. For example, a picoaccess point may provide coverage (e.g., coverage within a commercialbuilding) over an area that is smaller than a macro area and larger thana femto cell area. In various applications, other terminology may beused to reference a macro access point, a small cell, or other accesspoint-type nodes. For example, a macro access point may be configured orreferred to as an access node, base station, access point, eNodeB, macrocell, and so on. In some implementations, a node may be associated with(e.g., referred to as or divided into) one or more cells or sectors. Acell or sector associated with a macro access point, a femto accesspoint, or a pico access point may be referred to as a macro cell, afemto cell, or a pico cell, respectively.

FIG. 9 illustrates a wireless communication system 900, configured tosupport a number of users, in which the teachings herein may beimplemented. For example, the access terminals 906 and the access points904 may be LBEs and include a bandwidth manager 120 (FIG. 1). The accessterminals 906 and/or the access points 904 may implement the method 200illustrated in FIG. 2. The system 900 provides communication formultiple cells 902, such as, for example, macro cells 902A-902G, witheach cell being serviced by a corresponding access point 904 (e.g.,access points 904A-904G). As shown in FIG. 9, access terminals 906(e.g., access terminals 906A-906L) may be dispersed at various locationsthroughout the system over time. Each access terminal 906 maycommunicate with one or more access points 904 on a forward link (FL)and/or a reverse link (RL) at a given moment, depending upon whether theaccess terminal 906 is active and whether it is in soft handoft, forexample. The wireless communication system 900 may provide service overa large geographic region. For example, macro cells 902A-902G may covera few blocks in a neighborhood or several miles in a rural environment.

FIG. 10 illustrates an example of a communication system 1000 where oneor more small cells are deployed within a network environment. Thecommunication system 1000 may include one or more LBEs. For example, thesmall cells 1010 and access terminals 1020 may be LBEs including abandwidth manager 120 for determining channels to use for transmissions.A small cell 1010 and/or an access terminal 1020 may implement themethod 200 illustrated in FIG. 2. Specifically, the system 1000 includesmultiple small cells 1010 (e.g., small cells 1010A and 1010B) installedin a relatively small scale network environment (e.g., in one or moreuser residences 1030). Each small cell 1010 may be coupled to a widearea network 1040 (e.g., the Internet) and a mobile operator corenetwork 1050 via a DSL router, a cable modem, a wireless link, or otherconnectivity means (not shown). As will be discussed below, each smallcell 1010 may be configured to serve associated access terminals 1020(e.g., access terminal 1020A) and, optionally, other (e.g., hybrid oralien) access terminals 1020 (e.g., access terminal 1020B). In otherwords, access to small cells 1010 may be restricted whereby a givenaccess terminal 1020 may be served by a set of designated (e.g., home)small cell(s) 1010 but may not be served by any non-designated smallcells 1010 (e.g., a neighbor's small cell 1010).

FIG. 11 illustrates an example of a coverage map 1100 where severaltracking areas 1102 (or routing areas or location areas) are defined,each of which includes several macro coverage areas 1104. One or moreLBEs, each including a bandwidth management component 120 (FIG. 1) mayoperate within a tracking area 1102. Here, areas of coverage associatedwith tracking areas 1102A, 1102B, and 1102C are delineated by the widelines and the macro coverage areas 1104 are represented by the largerhexagons. The tracking areas 1102 also include femto coverage areas1106. In this example, each of the femto coverage areas 1106 (e.g.,femto coverage areas 1106B and 1106C) is depicted within one or moremacro coverage areas 1104 (e.g., macro coverage areas 1104A and 1104B).It should be appreciated, however, that some or all of a femto coveragearea 1106 might not lie within a macro coverage area 1104. In practice,a large number of femto coverage areas 1106 (e.g., femto coverage areas1106A and 1106D) may be defined within a given tracking area 1102 ormacro coverage area 1104. Also, one or more pico coverage areas (notshown) may be defined within a given tracking area 1102 or macrocoverage area 1104.

Referring again to FIG. 10, the owner of a small cell 1010 may subscribeto mobile service, such as, for example, 3G mobile service, offeredthrough the mobile operator core network 1050. In addition, an accessterminal 1020 may be capable of operating both in macro environments andin smaller scale (e.g., residential) network environments. In otherwords, depending on the current location of the access terminal 1020,the access terminal 1020 may be served by a macro cell access point 1060associated with the mobile operator core network 1050 or by any one of aset of small cells 1010 (e.g., the small cells 1010A and 1010B thatreside within a corresponding user residence 1030). For example, when asubscriber is outside his home, he is served by a standard macro accesspoint (e.g., access point 1060) and when the subscriber is at home, heis served by a small cell (e.g., small cell 1010A). Here, a small cell1010 may be backward compatible with legacy access terminals 1020.

A small cell 1010 may be deployed on a single frequency or, in thealternative, on multiple frequencies. Depending on the particularconfiguration, the single frequency or one or more of the multiplefrequencies may overlap with one or more frequencies used by a macroaccess point (e.g., access point 1060). As discussed above, the smallcell 1010 and/or an access terminal 1020 may include a bandwidth manager120 for selecting one or more frequencies to use for a transmissionbased, in part, on the usage by macro access point 1060.

In some aspects, an access terminal 1020 may be configured to connect toa preferred small cell (e.g., the home small cell of the access terminal1020) whenever such connectivity is possible. For example, whenever theaccess terminal 1020A is within the user's residence 1030, it may bedesired that the access terminal 1020A communicate only with the homesmall cell 1010A or 1010B.

In some aspects, if the access terminal 1020 operates within the macrocellular network 1050 but is not residing on its most preferred network(e.g., as defined in a preferred roaming list), the access terminal 1020may continue to search for the most preferred network (e.g., thepreferred small cell 1010) using a better system reselection (BSR)procedure, which may involve a periodic scanning of available systems todetermine whether better systems are currently available andsubsequently acquire such preferred systems. The access terminal 1020may limit the search for specific band and channel. For example, one ormore femto channels may be defined whereby all small cells (or allrestricted small cells) in a region operate on the femto channel(s). Thesearch for the most preferred system may be repeated periodically. Upondiscovery of a preferred small cell 1010, the access terminal 1020selects the small cell 1010 and registers on it for use when within itscoverage area.

Access to a small cell may be restricted in some aspects. For example, agiven small cell may only provide certain services to certain accessterminals. In deployments with so-called restricted (or closed) access,a given access terminal may only be served by the macro cell mobilenetwork and a defined set of small cells (e.g., the small cells 1010that reside within the corresponding user residence 1030). In someimplementations, an access point may be restricted to not provide, forat least one node (e.g., access terminal), at least one of: signaling,data access, registration, paging, or service.

In some aspects, a restricted small cell (which may also be referred toas a Closed Subscriber Group Home NodeB) is one that provides service toa restricted provisioned set of access terminals. This set may betemporarily or permanently extended as necessary. In some aspects, aClosed Subscriber Group (CSG) may be defined as the set of access points(e.g., small cells) that share a common access control list of accessterminals.

Various relationships may thus exist between a given small cell and agiven access terminal. For example, from the perspective of an accessterminal, an open small cell may refer to a small cell with unrestrictedaccess (e.g., the small cell allows access to any access terminal). Arestricted small cell may refer to a small cell that is restricted insome manner (e.g., restricted for access and/or registration). A homesmall cell may refer to a small cell on which the access terminal isauthorized to access and operate on (e.g., permanent access is providedfor a defined set of one or more access terminals). A hybrid (or guest)small cell may refer to a small cell on which different access terminalsare provided different levels of service (e.g., some access terminalsmay be allowed partial and/or temporary access while other accessterminals may be allowed full access). An alien small cell may refer toa small cell on which the access terminal is not authorized to access oroperate on, except for perhaps emergency situations (e.g., emergency-911calls).

From a restricted small cell perspective, a home access terminal mayrefer to an access terminal that is authorized to access the restrictedsmall cell installed in the residence of that access terminal's owner(usually the home access terminal has permanent access to that smallcell). A guest access terminal may refer to an access terminal withtemporary access to the restricted small cell (e.g., limited based ondeadline, time of use, bytes, connection count, or some other criterionor criteria). An alien access terminal may refer to an access terminalthat does not have permission to access the restricted small cell,except for perhaps emergency situations, for example, such as 911 calls(e.g., an access terminal that does not have the credentials orpermission to register with the restricted small cell).

For convenience, the disclosure herein describes various functionalityin the context of a small cell. It should be appreciated, however, thata pico access point may provide the same or similar functionality for alarger coverage area. For example, a pico access point may berestricted, a home pico access point may be defined for a given accessterminal, and so on.

The teachings herein may be employed in a wireless multiple-accesscommunication system that simultaneously supports communication formultiple wireless access terminals. Here, each terminal may communicatewith one or more access points via transmissions on the forward andreverse links. The forward link (or downlink) refers to thecommunication link from the access points to the terminals, and thereverse link (or uplink) refers to the communication link from theterminals to the access points. This communication link may beestablished via a single-in-single-out system, amultiple-in-multiple-out (MIMO) system, or some other type of system.

A MIMO system employs multiple (N_(T)) transmit antennas and multiple(N_(R)) receive antennas for data transmission. A MIMO channel formed bythe N_(T) transmit and N_(R) receive antennas may be decomposed intoN_(S) independent channels, which are also referred to as spatialchannels, where N_(S)≦min {N_(T), N_(R)}. Each of the N_(S) independentchannels corresponds to a dimension. The MIMO system may provideimproved performance (e.g., higher throughput and/or greaterreliability) if the additional dimensionalities created by the multipletransmit and receive antennas are utilized.

A MIMO system may support time division duplex (TDD) and frequencydivision duplex (FDD). In a TDD system, the forward and reverse linktransmissions are on the same frequency region so that the reciprocityprinciple allows the estimation of the forward link channel from thereverse link channel. This enables the access point to extract transmitbeam-forming gain on the forward link when multiple antennas areavailable at the access point.

FIG. 12 illustrates in more detail the components of a wireless device1210 (e.g., a small cell AP) and a wireless device 1250 (e.g., a UE) ofa sample communication system 1200 that may be adapted as describedherein. For example, each of wireless device 1210 and wireless device1250 may include a bandwidth manager 120 for determining which channelsto use for transmissions. Either the wireless device 1210 or thewireless device 1250 may implement the method illustrated in FIG. 2. Thebandwidth manager 120 may be a separate component or may be implementedby components such as TX data processor 1214 and TX MIMO processor 1220of wireless device 1210 or by TX data processor 1238 of device 1250. Atthe device 1210, traffic data for a number of data streams is providedfrom a data source 1212 to a transmit (TX) data processor 1214. Eachdata stream may then be transmitted over a respective transmit antenna.

The TX data processor 1214 formats, codes, and interleaves the trafficdata for each data stream based on a particular coding scheme selectedfor that data stream to provide coded data. The coded data for each datastream may be multiplexed with pilot data using OFDM techniques. Thepilot data is typically a known data pattern that is processed in aknown manner and may be used at the receiver system to estimate thechannel response. The multiplexed pilot and coded data for each datastream is then modulated (i.e., symbol mapped) based on a particularmodulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for thatdata stream to provide modulation symbols. The data rate, coding, andmodulation for each data stream may be determined by instructionsperformed by a processor 1230. A data memory 1232 may store programcode, data, and other information used by the processor 1230 or othercomponents of the device 1210.

The modulation symbols for all data streams are then provided to a TXMIMO processor 1220, which may further process the modulation symbols(e.g., for OFDM). The TX MIMO processor 1220 then provides NT modulationsymbol streams to NT transceivers (XCVR) 1222A through 1222T. In someaspects, the TX MIMO processor 1220 applies beam-forming weights to thesymbols of the data streams and to the antenna from which the symbol isbeing transmitted.

Each transceiver 1222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. NTmodulated signals from transceivers 1222A through 1222T are thentransmitted from NT antennas 1224A through 1224T, respectively.

At the device 1250, the transmitted modulated signals are received by NRantennas 1252A through 1252R and the received signal from each antenna1252 is provided to a respective transceiver (XCVR) 1254A through 1254R.Each transceiver 1254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

A receive (RX) data processor 1260 then receives and processes the NRreceived symbol streams from NR transceivers 1254 based on a particularreceiver processing technique to provide NT “detected” symbol streams.The RX data processor 1260 then demodulates, deinterleaves, and decodeseach detected symbol stream to recover the traffic data for the datastream. The processing by the RX data processor 1260 is complementary tothat performed by the TX MIMO processor 1220 and the TX data processor1214 at the device 1210.

A processor 1270 periodically determines which pre-coding matrix to use(discussed below). The processor 1270 formulates a reverse link messagecomprising a matrix index portion and a rank value portion. A datamemory 1272 may store program code, data, and other information used bythe processor 1270 or other components of the device 1250.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 1238,which also receives traffic data for a number of data streams from adata source 1236, modulated by a modulator 1280, conditioned by thetransceivers 1254A through 1254R, and transmitted back to the device1210. The bandwidth manager 120 may determine the channels used by TXdata processor 1238.

At the device 1210, the modulated signals from the device 1250 arereceived by the antennas 1224, conditioned by the transceivers 1222,demodulated by a demodulator (DEMOD) 1240, and processed by a RX dataprocessor 1242 to extract the reverse link message transmitted by thedevice 1250. The processor 1230 then determines which pre-coding matrixto use for determining the beam-forming weights then processes theextracted message.

It will be appreciated that for each device 1210 and 1250 thefunctionality of two or more of the described components may be providedby a single component. It will be also be appreciated that the variouscommunication components illustrated in FIG. 12 and described above maybe further configured as appropriate to perform communication adaptationas taught herein. For example, the processors 1230/1270 may cooperatewith the memories 1232/1272 and/or other components of the respectivedevices 1210/1250 to perform the communication adaptation as taughtherein.

FIG. 13 illustrates an example access point apparatus 1300 representedas a series of interrelated functional modules. A module for obtainingtraining data 1302 may correspond at least in some aspects to, forexample, a LBE such as an access terminal or access point as discussedherein. A module for determining that at least a first channel of theplurality of channels is available 1304 may correspond at least in someaspects to, for example, a processing system as discussed herein. Amodule for determining whether to wait for an additional channel 1306may correspond at least in some aspects to, for example, a processingsystem in conjunction with a communication device as discussed herein. Amodule for transmitting 1308 may correspond at least in some aspects to,for example, a transmitter in conjunction with a communication device asdiscussed herein.

The functionality of the modules of FIG. 13 may be implemented invarious ways consistent with the teachings herein. In some aspects, thefunctionality of these modules may be implemented as one or moreelectrical components. In some aspects, the functionality of theseblocks may be implemented as a processing system including one or moreprocessor components. In some aspects, the functionality of thesemodules may be implemented using, for example, at least a portion of oneor more integrated circuits (e.g., an ASIC). As discussed herein, anintegrated circuit may include a processor, software, other relatedcomponents, or some combination thereof. Thus, the functionality ofdifferent modules may be implemented, for example, as different subsetsof an integrated circuit, as different subsets of a set of softwaremodules, or a combination thereof. Also, it should be appreciated that agiven subset (e.g., of an integrated circuit and/or of a set of softwaremodules) may provide at least a portion of the functionality for morethan one module.

In addition, the components and functions represented by FIG. 13 as wellas other components and functions described herein, may be implementedusing any suitable means. Such means also may be implemented, at leastin part, using corresponding structure as taught herein. For example,the components described above in conjunction with the “module for”components of FIG. 13 also may correspond to similarly designated “meansfor” functionality. Thus, in some aspects one or more of such means maybe implemented using one or more of processor components, integratedcircuits, or other suitable structure as taught herein.

In some aspects, an apparatus or any component of an apparatus may beconfigured to (or operable to or adapted to) provide functionality astaught herein. This may be achieved, for example: by manufacturing(e.g., fabricating) the apparatus or component so that it will providethe functionality; by programming the apparatus or component so that itwill provide the functionality; or through the use of some othersuitable implementation technique. As one example, an integrated circuitmay be fabricated to provide the requisite functionality. As anotherexample, an integrated circuit may be fabricated to support therequisite functionality and then configured (e.g., via programming) toprovide the requisite functionality. As yet another example, a processorcircuit may execute code to provide the requisite functionality.

It should be understood that any reference to an element herein using adesignation such as “first,” “second,” and so forth does not generallylimit the quantity or order of those elements. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. Also, unless stated otherwise a setof elements may comprise one or more elements. In addition, terminologyof the form “at least one of A, B, or C” or “one or more of A, B, or C”or “at least one of the group consisting of A, B, and C” used in thedescription or the claims means “A or B or C or any combination of theseelements.” For example, this terminology may include A, or B, or C, or Aand B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so on.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

Accordingly, an aspect of the disclosure can include a computer readablemedium embodying a method for dynamic bandwidth management fortransmissions in unlicensed spectrum. Accordingly, the disclosure is notlimited to the illustrated examples.

While the foregoing disclosure shows illustrative aspects, it should benoted that various changes and modifications could be made hereinwithout departing from the scope of the disclosure as defined by theappended claims. The functions, steps and/or actions of the methodclaims in accordance with the aspects of the disclosure described hereinneed not be performed in any particular order. Furthermore, althoughcertain aspects may be described or claimed in the singular, the pluralis contemplated unless limitation to the singular is explicitly stated.

What is claimed is:
 1. A method for dynamic bandwidth management, themethod comprising: obtaining training data by monitoring a plurality ofchannels in an unlicensed spectrum during a training period; determiningthat at least a first channel of the plurality of channels is availablefor a transmission; and determining, based on the training data, whetherto wait for an additional channel of the plurality of channels to becomeavailable for the transmission.
 2. The method of claim 1, whereinobtaining the training data comprises: estimating, for a set of channelstates, a corresponding set of probabilities indicating likelihoods thatno additional channel is to become available within a transmissionopportunity following the transmission.
 3. The method of claim 2,wherein estimating the probability that no additional channel is tobecome available comprises: determining, for a plurality of transmissiontimes during the training period, whether the additional channel hasbecome available during a transmission opportunity following each of theplurality of transmission times; associating each of the plurality oftransmission times with a respective channel state of the set of channelstates at the transmission time; and determining a portion of theplurality of transmission times for each channel state where noadditional channel has become available.
 4. The method of claim 2,wherein the set of channel states is based on a number of availablechannels at the respective transmission time.
 5. The method of claim 2,wherein the set of channel states is based on a combination of availablechannels at the respective transmission time.
 6. The method of claim 2,wherein determining whether to wait for the additional channelcomprises: selecting a first probability from the set of probabilitiesbased on a first channel state from the set of channel states, whereinthe first channel state is a current channel state; generating a firstrandom or pseudo-random number, and waiting for the additional channelwhen the first random or pseudo-random number exceeds a first thresholdvalue, wherein the first threshold value is based on the probability. 7.The method of claim 6, further comprising: determining that a firstadditional channel has become available; selecting a second probabilityfrom the set of probabilities based on a second channel state from theset of channel states; generating a second random or pseudo-randomnumber; and waiting for a second additional channel when the secondrandom or pseudo-random number exceeds a second threshold value, whereinthe second threshold value is based on the second probability.
 8. Themethod of claim 1, wherein obtaining the training data comprises:collecting a plurality of samples for potential transmission timeshaving at least one available channel of the plurality of channels, eachsample indicating states of a plurality of backoff counterscorresponding respectively to the plurality of channels; and evaluatingeach sample to determine whether the transmission time of the sample isa good transmission time.
 9. The method of claim 8, wherein determining,based on the training data, whether to wait for an additional channel ofthe plurality of channels to become available for the transmissioncomprises using a machine learning classifier to classify a currentcounter state vector for the plurality of channels based on theplurality of samples.
 10. The method of claim 9, further comprisingseparating the plurality of samples into different sets based on anumber of available channels of each sample, wherein using a machinelearning classifier to classify a current counter state vector comprisesusing the machine learning classifier to classify the current counterstate vector based on the set corresponding to a number of availablechannels of the current counter state vector.
 11. The method of claim 8,wherein determining that the transmission time of the sample is a goodtransmission time comprises determining that a number of availablechannels did not increase during a transmission opportunity followingthe transmission time.
 12. The method of claim 8, wherein determiningthat the transmission time of the sample is a good transmission timecomprises determining that an available bandwidth of the availablechannels did not increase during a transmission opportunity followingthe transmission time.
 13. The method of claim 8, wherein the state of abackoff counter from the plurality of backoff counters corresponding toan available channel indicates an amount of time that the availablechannel has been available.
 14. The method of claim 1, furthercomprising waiting for a duration of a transmission opportunity andtransmitting on the at least one channel when no additional channelsbecome available during the duration of the transmission opportunity.15. An apparatus for dynamic bandwidth management, comprising: a channelassessing component configured to obtain training data by monitoring aplurality of channels in an unlicensed spectrum during a trainingperiod; a training component configured to determine that at least afirst channel of the plurality of channels is available for atransmission; and a channel selecting component configured to determine,based on the training data, whether to wait for an additional channel ofthe plurality of channels to become available for the transmission. 16.The apparatus of claim 15, wherein the training component is furtherconfigured to estimate, for a set of channel states, a corresponding setof probabilities indicating likelihoods that no additional channel is tobecome available within a transmission opportunity following thetransmission.
 17. The apparatus of claim 16, wherein the trainingcomponent is further configured to: determine, for a plurality oftransmission times during the training period, whether the additionalchannel has become available during a transmission opportunity followingeach of the plurality of transmission times; associate each of theplurality of transmission times with a respective channel state of theset of channel states at the transmission time; and determine a portionof the plurality of transmission times for each channel state where noadditional channel has become available.
 18. The apparatus of claim 16,wherein the set of channel states is based on a number of availablechannels at the respective transmission time.
 19. The apparatus of claim16, wherein the set of channel states is based on a combination ofavailable channels at the respective transmission time.
 20. Theapparatus of claim 16, wherein the channel selecting component isfurther configured to: select a first probability from the set ofprobabilities based on a first channel state from the set of channelstates, wherein the first channel state is a current channel state;generate a first random or pseudo-random number; and wait for theadditional channel when the first random or pseudo-random number exceedsa first threshold value, wherein the first threshold value is based onthe probability.
 21. The apparatus of claim 20, wherein the channelselecting component is further configured to: determine that a firstadditional channel has become available; select a second probabilityfrom the set of probabilities based on a second channel state from theset of channel states; generate a second random or pseudo-random number;and wait for a second additional channel when the second random orpseudo-random number exceeds a second threshold value, wherein thesecond threshold value is based on the second probability.
 22. Theapparatus of claim 15, wherein the training component is furtherconfigured to: collect a plurality of samples for potential transmissiontimes having at least one available channel of the plurality ofchannels, each sample indicating states of a plurality of backoffcounters corresponding respectively to the plurality of channels; andevaluate each sample to determine whether the transmission time of thesample is a good transmission time.
 23. The apparatus of claim 22,wherein the channel selecting component further comprises a machinelearning classifier configured to classify a current counter statevector for the plurality of channels based on the plurality of samples.24. The apparatus of claim 23, wherein the machine learning classifieris further configured to separate the plurality of samples intodifferent sets based on a number of available channels of each sample,and classify the current counter state vector based on the setcorresponding to a number of available channels of the current counterstate vector.
 25. The apparatus of claim 22, wherein determining thatthe transmission time of the sample is a good transmission timecomprises determining that a number of available channels did notincrease during a transmission opportunity following the transmissiontime.
 26. The apparatus of claim 22, wherein determining that thetransmission time of the sample is a good transmission time comprisesdetermining that an available bandwidth of the available channels didnot increase during a transmission opportunity following thetransmission time.
 27. The apparatus of claim 22, wherein the state of abackoff counter from the plurality of backoff counters corresponding toan available channel indicates an amount of time that the availablechannel has been available.
 28. The apparatus of claim 15, wherein thechannel selecting component is configured to wait for a duration of atransmission opportunity and transmit on the at least one channel whenno additional channels become available during the duration of thetransmission opportunity.
 29. An apparatus for dynamic bandwidthmanagement, comprising: means for obtaining training data by monitoringa plurality of channels in an unlicensed spectrum during a trainingperiod; means for determining that at least a first channel of theplurality of channels is available for a transmission; and means fordetermining, based on the training data, whether to wait for anadditional channel of the plurality of channels to become available forthe transmission.
 30. A computer readable medium storing computerexecutable code, comprising: code for obtaining training data bymonitoring a plurality of channels in an unlicensed spectrum during atraining period; code for determining that at least a first channel ofthe plurality of channels is available for a transmission; and code fordetermining, based on the training data, whether to wait for anadditional channel of the plurality of channels to become available forthe transmission.